DML
主要是对表中的数据进行增、删、改的操作
所有的操作以下面emp为例
+------+-----------+--------+------------+------------+------+--------+---------+-------+
| id | userName | gender | birthday | entry_date | job | salary | resume | image |
+------+-----------+--------+------------+------------+------+--------+---------+-------+
| 2 | toneTwo | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 3 | toneThree | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 4 | toneFour | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 5 | toneFive | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 1 | toneOne | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 6 | toneSix | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
+------+-----------+--------+------------+------------+------+--------+---------+-------+
一、查询表中所有的数据
SELECT * FROM emp
+------+-----------+--------+------------+------------+------+--------+---------+-------+
| id | userName | gender | birthday | entry_date | job | salary | resume | image |
+------+-----------+--------+------------+------------+------+--------+---------+-------+
| 2 | toneTwo | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 3 | toneThree | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 4 | toneFour | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 5 | toneFive | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 1 | toneOne | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 6 | toneSix | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
+------+-----------+--------+------------+------------+------+--------+---------+-------+
二、数据库中插入数据操作
INSERT INTO emp(id, userName, gender, birthday, entry_date, job, salary, resume, image) VALUES
(7, "wangwu", "man", "1992-01-29", "2019-03-29", "iOS", 50000, "good boy", "2345555");
+------+-----------+--------+------------+------------+------+--------+----------+---------+
| id | userName | gender | birthday | entry_date | job | salary | resume | image |
+------+-----------+--------+------------+------------+------+--------+----------+---------+
| 2 | toneTwo | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 3 | toneThree | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 4 | toneFour | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 5 | toneFive | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 1 | toneOne | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 6 | toneSix | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 7 | wangwu | man | 1992-01-29 | 2019-03-29 | iOS | 50000 | good boy | 2345555 | 新插入的数据
+------+-----------+--------+------------+------------+------+--------+----------+---------+
三、更新表中所有工资的数据我
UPDATE emp SET salary=5000;
四、带条件更新表中的数据
UPDATE emp SET salary=2000 WHERE userName="wangwu";
修改 wangwu 的工资 2000
+------+-----------+--------+------------+------------+------+--------+----------+---------+
| id | userName | gender | birthday | entry_date | job | salary | resume | image |
+------+-----------+--------+------------+------------+------+--------+----------+---------+
| 2 | toneTwo | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 3 | toneThree | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 4 | toneFour | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 5 | toneFive | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 1 | toneOne | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 6 | toneSix | enger | 2015-09-30 | 2015-08-23 | NULL | 5000 | goodboy | NULL |
| 7 | wangwu | man | 1992-01-29 | 2019-03-29 | iOS | 2000 | good boy | 2345555 |
+------+-----------+--------+------------+------------+------+--------+----------+---------+
五、删除表中某一条数据
DELETE FROM emp WHERE userName='wangwu';
六、删除表中所有的数据（直接先删除表，然后再创建一个新的表）
TRUNCATE TABLE emp;
DELETE 删除之后数据还能够找回，TRUNCATE： 删除数据无法找回
网友评论